CZ550 Magnum Receiver

[lelongcarabine]

Met a Gentleman at the Rifle Range, today. He was shooting a custom CZ-550 in .338 Lapua Magnum. It had a Hart barrel w/brake and IOR Valdada optics! WOW!
Questions;
#1. Anyone have any experience fitting barrels to this action. Metric or English threads?
#2. Are they a quality receiver? Accuracy upgrades or blueprinting required? Piccatinny scope bases available?
#3. Where do you buy receivers, only?
#4. Are they adequate for the .338 Lapua Magnum cartridge?
I have a single shot target receiver for that cartridge. However, it weighs a lot more than a CZ 550. It is huge.
Any ideas or thoughts? Thanks in advance! Greg

 

[butchlambert]

I have one that I built into a 458 Lott. They definitely need blueprinting and a custom trigger. They build a couple models of magnum receivers. Don't know if they make one that will work well with the 338 Lapua. I may have bought mine from Brownells.
Butch

 

[p17enfeild]

thay make one for .416 rigby, they are well up to the task,
threads are matric triger will need work

they make for a nice light .338 lapua hunter,

 

[wboggs]

I have a .458 Lott that has been trued, trigger honed, bedded with heavy recoil lugs. It is a strong reciever and the magazine well holds 5 .458s. I checked it with 450 Dakota rounds, a .416 Rigby size case, and they fit easily. Mine is quite accurate with just over 1" grps at 100 yds using handloads. Function is flawless everytime. I saw a Brevex Mauser in Africa and it is heavier but the action alone cost around $3000. There are gunsmiths who wii machine one from scratch with any option you can think of. All you need is money.
You can probably pick up a CZ at a reasonable price, rebarrel, stock, trigger adjustment or change for $2500-3000.
Bill

 

[lelongcarabine]

WBoggs, Thanks for your reply and PM. I can do the 'smithing. Just need an action. Would make a very fine LR elk rifle, I'm thinking. Just wish there were good quality, magazine fed AMERICAN MADE Receivers available for the .338 LAPUA, more sturdy than the Remington 700's recently introduced! Surgeon makes one, I know, but that is VERY Pricey! I do have a budget! Money is an object! Greg

 

[D-mon]

Hi,
What about converting a P17 action?
A-Square has built the 577 Tyrannosaurus out of it, it should be able to handle the 338 lapua?
I dont know which of the 3 actions would be the best?:
remington, Edison or winchester?

Maybe not the tolerances of a surgeon action, but with the right barrel and in the hands of a good smith should be able to get arround the moa?
Just a thought
ND

 

[shortgrass]

Look at at Stillers' TAC338 Action. $1050 retail price. By the time all the modifications would be complete, on a P14/P17, you'd have a cock on closing action with that much in it. The Eddystone (Edison?) was known for poor heat treat and is even avoided as a shooter today. P14/P17s, in any kind of condition, are too valuable as collectors to chop up. No 'cheap' way to get that .338L and have something when you're done! If price is your motivator, buy a Savage. Or give up and buy the imported CZ. Sometimes "Simmons Sport Specialities" (sells to FFL only) has CZ actions as does Brownells (mentioned above).

 

[lelongcarabine]

Respect to all! Thanks for your input 8).
I would never consider a 1917 Enfield as most are collectors items today. Years ago, I modified 1917's for sporters. Ground off rear sight ears and welded "swimming pools" and replaced dog legged bolt handles. Square receiver threads are a 150+ year old design that was used in the .52 caliber Sharps combustable cartridge breech loaders and 1873 Springfields. Not what I want on a LR rifle with a large diameter, high pressure cartridge.
If a rifle is shooting only 1 MOA it needs serious help or a new barrel !
I wont "buy a Savage"! Same reason as the Remington 700! The receiver diameter is to small(IMHO) for the cartridge diameter/operating pressures generated by the .338 Lapua.
The cost of a Barrel Blank, Reamer and headspace gauge are known quantities.
A receiver is the heart of the project. I want rigidity, mechanical alignment and reliability. I have an American Arms and Ordinance Long Range Receiver with the proper bolt face. It is a single shot and it is HUGE! I'd have to hire a "gun Bearer" to carry the dang thing ;D! For a BR rifle it would be ideal!
I would also like a magazine feed.
Now, there are the Sako TRG and the AI and Barrett tactical rifles available, at the top end. If I was to buy a .338 Lapua, that is where I would go! However, I am seeking a balance. Quality components without breaking the bank and willing sweat equity, which I have.
I have considered using the receiver from a .30 or .338/378 Weatherby. I know of one that could/may be accessed with a shot out barrel. Just am not familiar with that receiver.
Anyone have knowledge of the Weatherby?
These are my thoughts. I love spirited discussion. Please keep the input coming!
Thanks! Greg

 

[Larryh128]

Go to Brownells #64 catalog on page 148. Thread is M28x2sp3. Looks like about $700. There is a Bauska Magnum Mauser action on Gunbroker right now that would fit the bill as well.

 

[lelongcarabine]

Yep! Found it! Thanks! Looks different in the catalog!
$682.86 plus shipping, insurance, FFL holder fee and background instant check fee. STILL, Not a bad deal!
Metric thread questions. M28 is the Major diameter of 28MM?
2 is the number of threads per MM? "sp3" is the fit class?
Anyone know the barrel tenon length? Greg

 

[shortgrass]

The #2 is the distance the thread advances in one, complete revolution. Not threads per MM.

 

[lelongcarabine]

shortgrass, Thats a very coarse thread! If the tenon advances 2 MM in one revolution, that gives the thread a pitch of (English) .0787".or (conversion) 12.7 TPI. I have to get my head wrapped around this Metric stuff. My Lathe will cut metric pitch, however, I am going to go to school on this one 8) ;D. Greg

 

[shortgrass]

Consider that the Mauser '93 thru '98s use 12 tpi. The '93 thru '96, .980"x12 and the large ring '98, 1.100"x12 tpi. 28(mm)x .0394=1.103". Real close to the '98, and there a literally millions of those "out there" that have been 'sporterized into every imaginable chambering. Remember,, action design is based on chamber pressure/bolt thrust, not bullet diameter. Is your lathe one where you can disengage the split nut or does it have to stay engaged until the metric thread is complete?

 

[lelongcarabine]

shortgrass, I did a 98 Mauser barrel job 40 years ago with hand ground REX95 tool bits to cut the buttress thread. However, I havent worked a Metric thread since.
The lathe has the capability to do either SAE or Metric. The half-nuts must be engaged. Is the thread a 60* or other geometry? Thanks, Greg

 

[butchlambert]

98 Mausers do not have buttress threads. A M1917 Enfield will handle any cartridge that you can think of. I have brass out of a couple friends rifles. One is the .585 AHR and the other is a 600 Overkill. I am building a 416 Rigby out of mine.
This is the start of mine and the custom bases.

This shows the custom bolt handle and the surface ground rear ring.

This shows the custom trigger and bottom metal. A custom bolt release should be done next week.

As mentioned before, to do one right you will have at least twice the money in the receiver as you would a CZ550.
Butch

 

[shortgrass]

I believe those 55* threads Mauser used are known a Whitworth not Buttress, as Butch pointed out. Nice bolt handle, Butch. Did you weld it? I think the threads CZ uses are 60*, but, I don't know that for sure. Usually, if in a modern designation, if they are other than 60* the angle is part of the designation. SP3 is a 'special' metric thread, special only in its' tolerance.

 

[butchlambert]

Nick Hughes in Okla. did the surface grind, bolt handle, and bases. He is making the bolt release also. Duane Wiebe did the bottom metal.
On another note. The vast majority of the custom gunmakers use a 60deg. threading tool on the 98 mausers and not the 55deg. It has been argued for years, but it really is a non issue.
Butch

 

[lelongcarabine]

ButchLambert, Military 1898 Mausers DO have Buttress threads. I still have the threading tool! 40 years ago, Military surplus 98 and 98K Mausers were $10-$25 and could be found almost anywhere guns were sold. They had the slot on the left side of the receiver to clear your thumb when loading from a stripper clip. The barrel tenon had two points of contact with the receiver and required a very tight tolerance on the tenon length to get an equal amount of shoulder engagement between the inner and outer shoulder. However, that Mauser model is not an issue. Its to small.
Yes a 1917 will handle this round. However, I have no access to a 1917, even though I could do the work. Its not a desirable option. I reworked 1917's years ago and I do not like them!
Your workmanship looks great! Thanks for your extra effort to provide pictures.
Yes! The commercial Mauser actions have V threads including the Magnum Mauser action. However, we are talking two different animals, here.
Now its decision time! Do I build a BR rifle or a Hunting rifle?
I'd like both but that is not an option. Greg

 

[lelongcarabine]

Been thinking, Old Timers Disease , takes its toll. I know that the cocking piece on those 98's was a buttress thread and I may have transferred it to my memory :'(! However, I do remember a 55* Whitworth thread but dont remember the application :-\! Anyway, My apologies if I lead anyone down a bunny trail. Its been a LONG time!
Thanks for your input! Greg

 

[shortgrass]

Mauser '98,,, Buttress thread on the bolt scroud, 55* Whitworth on the barrel tenon. Most use a 60* when re-barreling (except me, I still use 55*).